[PATCH 1/2 v2] PCI: Add PCI_DEV_FLAGS_USE_NON_MSI_INTX_IRQ to enable non MSI/INTx interrupt

[Liu Shengzhou-B36685]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Monday, July 16, 2012 11:47 PM
> To: Liu Shengzhou-B36685
> Cc: bhelgaas at google.com; linux-pci at vger.kernel.org; linuxppc-
> dev at lists.ozlabs.org
> Subject: Re: [PATCH 1/2 v2] PCI: Add PCI_DEV_FLAGS_USE_NON_MSI_INTX_IRQ to
> enable non MSI/INTx interrupt
> 
> On 07/15/2012 10:31 PM, Shengzhou Liu wrote:
> > On some platforms, in RC mode, root port has neither MSI/MSI-X nor
> > INTx interrupt generated, which are available only in EP mode on those
> platform.
> > In this case, we try to use other interrupt for port service driver to
> > have AER, Hot-plug, etc, services to work.
> >
> > Signed-off-by: Shengzhou Liu <Shengzhou.Liu at freescale.com>
> > ---
> > v2: separated platform-specific part to arch/powerpc/sysdev.
> >
> >  drivers/pci/pcie/portdrv_core.c |   10 ++++++++--
> >  drivers/pci/quirks.c            |    9 +++++++++
> >  include/linux/pci.h             |    5 +++++
> >  3 files changed, 22 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/portdrv_core.c
> > b/drivers/pci/pcie/portdrv_core.c index 75915b3..837ad15 100644
> > --- a/drivers/pci/pcie/portdrv_core.c
> > +++ b/drivers/pci/pcie/portdrv_core.c
> > @@ -212,8 +212,14 @@ static int init_service_irqs(struct pci_dev *dev, int
> *irqs, int mask)
> >  	if (!pcie_port_enable_msix(dev, irqs, mask))
> >  		return 0;
> >
> > -	/* We're not going to use MSI-X, so try MSI and fall back to INTx */
> > -	if (!pci_enable_msi(dev) || dev->pin)
> > +	/*
> > +	 * We're not going to use MSI-X, so try MSI and fall back to INTx.
> > +	 * Eventually, if neither MSI/MSI-X nor INTx available, try other
> > +	 * interrupt. (On some platforms, root port doesn't support generating
> > +	 * MSI/MSI-X/INTx in RC mode)
> > +	 */
> > +	if (!pci_enable_msi(dev) || dev->pin || ((dev->dev_flags &
> > +			PCI_DEV_FLAGS_USE_NON_MSI_INTX_IRQ) && dev->irq))
> >  		irq = dev->irq;
> 
> I didn't see a response on the question about what would happen if we did this
> unconditionally (i.e. just s/dev->pin/dev->irq/ in the original code).  We
> should avoid introducing flags like this unless there's a good reason.
> 
> Maybe submit a patch that does it unconditionally, and see if that draws a
> complaint.
> 
> -Scott
[Shengzhou] 
Well, the patch without flag condition have been posted to draw more comments.